Ted is played by Josh Radnor, and Robin is played by Cobie Smulders.
The characters are becoming so popular, they're being compared to Ross and Rachel of the old sitcom, "Friends."
But on The Early Show Monday, Radnor told co-anchor Rene Syler he's not sure the comparison is on-target.
"I don't think our show, I mean, other than (it being about) young people in New York, beyond that, the show's not really like 'Friends,' Radnor said. "I mean, the way we tell stories … it's almost like the whole show is a big mystery, 'Who is Ted gonna end up with?' and each episode is kind of a mystery. I just think it's fascinating. And the other thing is … the Ross and Rachel thing was, are they going to get together, or aren't they? We're together, and the question is, when are we gonna part? "
Radnor and Smulders also discussed possible plot twists, whether they're really like the characters they play in the sitcom, and more.
To see the interview,